Perth in October 2011: A warmer and wetter month

This statement was prepared before all data for the period were available. This may affect some of the statistics presented.
  • Rainfall: Average to above average.
  • Maximum temperature: Above average for most sites and 3rd warmest on record for Perth Metro.
  • Minimum temperature: Above average.

Rainfall

Rainfall across the Perth metropolitan area during October 2011 was near average or slightly below average in the southern suburbs, but the rest of the Perth area saw above to very much average rainfall. Rainfall totals were generally in the 30 to 80 mm range, and Rottnest Island received 75.6 mm, which was more than double its long-term average for October, and Rottnest Island's wettest October in 16 years. Perth Metro, Perth Airport, and Pearce RAAF also registered their highest October rainfall total in 12 years.

A middle level disturbance brought light showers to most sites in the Perth area during the first three days of October, though a couple of sites in the southern suburbs received rainfall of more than 10 mm. Isolated falls from showers and thunderstorms occurred in Perth between the 7th and 10th, with a notable fall of 24.6 mm at Jandakot on the 9th, whilst cold fronts on the 13th and 18th brough rain to the metropolitan area although falls were generally light. A series of middle level disturbances in the latter part of the month brought some significant falls to the Perth area. Shower and thunderstorms occurred on the 22nd, and on the 24th to 27th, with daily totals in the 10 to 30 mm range on the 25th and 27th. Daily rainfall of 30.0 mm at Pearce RAAF on the 25th was the highest daily total of the month for the Perth area.

Perth Metro recorded 64.2 mm on 9 rain days in October 2011, compared to the long-term average of 52.2 mm on 8.8 rain days. October rainfall totals have ranged from 1.0 mm in 1969 to 199.9 mm in 1890 at Perth Metro, whilst last October (2010), Perth Metro recorded 20.6 mm on 5 rain days.

For the year to date, Perth Metro has recorded 756.0 mm of rainfall on 95 rain days in the first 10 months of 2011, which is below the average of 815.1 mm, but despite this is the wettest January to October period in 6 years, since 856.4 mm was recorded on 113 rain days from January to October 2005.

Maximum temperature

Mean daily maximum temperatures were above average through the Perth Metropolitan area during October 2011, though sites close to the Perth hills were closer to average. Swanbourne registered a mean maximum temperature of 23.8 °C, 1.9 °C above average and the warmest October with respect to daytime temperatures in its 18 years of record.

The warmest day of the month across the Perth area was the 16th, when a strong high pressure in the Bight directed a dry and hot northeasterly airstream over western parts of WA. Daily maxima across Perth mainland sites ranged from the low to mid-30s, and were more than 10 °C warmer than normal for most sites. The 36.9 °C recorded at Gosnells City was the highest temperature of the month in the Perth region. The coldest day of the month across the Perth metropolitan area followed shortly after on the 18th, with daily maxima mostly in the 19 °C to 21 °C range on the coastal plain, whilst a maximum of 16.4 °C recorded at Bickley was the lowest daily maximum temperature of the month for the region.

Perth Metro's mean daily maximum temperature in October was 24.5 °C, which is the 3rd warmest October since records commenced in 1897, and follows on from last October's 24.6 °C, the 2nd warmest October on record. The warmest October on record at Perth Metro is 25.8 °C in 1969. Daily maxima in October 2011 ranged from a mild 19.8°C on the 18th, to a hot 36.3°C on the 16th.

Perth Metro's mean daily maximum temperature for the first 10 months of 2011 is 25.2°C, the warmest January to October period since records commenced in 1897. The previous record was 24.6°C in 1978, whilst the average for the same period is 23.9°C.

Minimum temperature

Mean minimum temperatures across Perth during October 2011 were very much above average, with several sites experiencing their warmest October nights on record. Rottnest Island recorded its warmest October in 35 years, since 1976, and 4th warmest October since records commenced in 1880.

Most nights were either mild or warm during the month, and the warmest night was the 16th, with daily minima in mid-to-high teens. Both Perth Metro and Swanbourne recorded a daily minimum temperature of 19.3 °C on the 16th, the highest overnight temperature of the month for the Perth area. The coldest night of the month was the 19th, with the daily minimum temperature of 4.9 °C at Pearce RAAF being the only temperature recorded below 5 °C for the month in the Perth metropolitan area.

Perth Metro's mean daily minimum temperature in October was 13.0 °C, which is the warmest October since records commenced at the Mt Lawley site in 1994. The average for October is 11.2°C. Daily minima ranged from a cool 7.2°C on the 14th to a warm 19.3°C on the 16th.

Wind and Sunshine

The greatest wind gust during the month in the Perth metropolitan area was 74 km/h recorded both Champion Lakes, on the 10th, and Perth Airport, on the 29th.

Perth recorded average daily sunshine of 8.6 hours in October 2011, 1 hours below the average of 9.6 hours per day, and the cloudiest October in Perth since 1993.

Further information

Media
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Extremes in October 2011
Hottest day 36.9 °C at Gosnells City on the 16th
Warmest days on average 24.9 °C at Gosnells City
Coolest days on average 21.2 °C at Bickley
Coldest day 16.4 °C at Bickley on the 18th
Coldest night 4.9 °C at Pearce RAAF on the 19th
Coolest nights on average 11.0 °C at Bickley
Warmest nights on average 15.0 °C at Rottnest Island
Warmest night 19.3 °C at Perth Metro on the 16th
19.3 °C at Swanbourne on the 16th
Wettest overall 82.6 mm at Mundaring
Wettest day 30.0 mm at Pearce RAAF on the 25th
Highest wind gust 74 km/h at Champion Lakes on the 10th
74 km/h at Perth Airport on the 29th

Highest total October rainfall for at least 10 years
Total rainfall
for October 2011 (mm)
Most recent October
this high or higher
Years since
higher
Average for
October
Rottnest Island 75.6 98.8 in 1995 16 31.2
Pearce RAAF 60.0 75.6 in 1999 12 37.1
Perth Airport 62.4 78.8 in 1999 12 44.8
Perth Metro 64.2 96.4 in 1999 12 41.0




Record highest October mean daily maximum temperature
Mean daily maximum
temperature
for October 2011 (°C)
Previous highest
for October
Years of
record
Average for
October
Swanbourne 23.8 23.6 in 2010 18 21.9



Record highest October mean daily minimum temperature
Mean daily minimum
temperature
for October 2011 (°C)
Previous highest
for October
Years of
record
Average for
October
Medina Research Centre 12.7 12.1 in 2008 24 10.2
Jandakot Aero 11.7 11.6 in 1991 21 9.4
Swanbourne 13.7 13.1 in 2008 18 12.0
Bickley 11.0 10.6 in 2008 17 9.4



Summary statistics for October 2011
Maximum temperatures
for October
(°C)
Minimum temperatures
for October
(°C)
Rainfall
for October
(millimetres)
Mean for
October
2011
Diff
from
average
Highest for
October
2011
Mean for
October
2011
Diff
from
average
Lowest for
October
2011
Total for
October
2011
Average
for
October
Rank of
October
2011
Fraction of
October
average
Bickley 21.2 +0.2 32.9 16th 11.0 +1.6 6.2 19th 78.8 67.2 average 117%
Champion Lakes 23.2   34.0 16th 13.5   8.4 19th  
Garden Island HSF 22.0   34.5 16th 14.3   9.3 7th 29.6 31.8 average 93%
Gosnells City 24.9 +1.2 36.9 16th         48.4 46.9 average 103%
Jandakot Aero 23.9 +1.4 35.8 16th 11.7 +2.3 5.4 5th 59.0 47.3 high 125%
Medina Research Centre 23.8 +1.3 36.8 16th 12.7 +2.5 6.0 19th 35.4 41.2 average 86%
Pearce RAAF 23.9 +0.6 35.5 16th 12.0 +2.0 4.9 19th 60.0 37.1 high 162%
Perth Airport 24.2 +1.6 36.1 16th 12.2 +2.0 6.8 14th 62.4 44.8 high 139%
Perth Metro 24.3 +1.3 36.3 16th 13.0 +1.8 7.2 14th 64.2 52.2 high 123%
Rottnest Island 21.4 +1.2 29.3 16th 15.0 +1.3 12.1 19th 75.6 37.1 v high 204%
Swanbourne 23.8 +1.9 35.9 16th 13.7 +1.7 8.1 19th 64.2 43.8 high 147%

Daily maximum temperature
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley25.919.218.318.319.821.821.319.923.023.322.319.117.419.325.432.919.616.418.421.826.823.720.419.618.917.820.420.022.023.5
Champion Lakes27.721.320.120.321.522.822.023.324.524.824.720.619.320.227.534.021.019.020.524.529.026.123.521.522.120.521.422.724.125.9
Garden Island HSF20.921.618.518.220.319.621.121.522.723.021.320.218.821.125.234.521.618.518.021.728.122.722.023.822.321.220.019.925.526.3
Gosnells City30.023.521.021.723.125.024.024.526.126.426.122.920.922.530.536.922.720.421.826.431.026.524.923.023.221.624.024.026.027.4
Jandakot Aero28.022.221.020.921.223.422.522.524.726.023.821.720.021.227.935.822.120.120.625.129.925.124.723.123.221.322.223.825.026.9
Medina Research Centre27.623.620.720.221.722.722.623.724.825.524.022.020.221.527.836.822.319.020.525.025.225.223.722.623.022.223.825.527.4
Pearce RAAF27.922.520.521.022.123.622.722.525.627.224.121.920.321.627.635.522.419.521.024.429.027.224.023.421.721.523.223.125.0
Perth Airport28.322.621.221.722.223.922.923.126.326.425.422.821.121.828.536.121.920.121.725.229.726.424.422.822.320.722.623.525.226.4
Perth Metro28.122.721.121.222.623.723.023.326.226.625.322.620.822.328.636.322.919.820.825.530.025.524.623.223.320.922.823.525.626.7
Rottnest Island23.521.319.118.420.020.020.721.121.521.821.219.619.920.724.529.320.519.017.920.627.923.420.822.320.019.921.119.622.223.5
Swanbourne26.322.820.420.620.721.921.522.326.827.422.821.820.522.627.735.921.820.120.225.430.622.624.623.222.121.222.222.926.627.7

This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.
The temperatures in this table are coloured by
their difference from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C difference from average


Daily minimum temperature
Central Coast (09)12345678910111213141516171819202122232425262728293031
Bickley10.113.311.211.59.110.010.411.711.59.311.412.512.29.311.514.614.411.66.26.49.115.212.810.311.913.213.09.27.98.710.8
Champion Lakes13.813.513.113.58.910.810.013.814.613.014.815.314.98.512.719.217.313.78.410.313.418.515.614.514.415.515.712.611.912.614.4
Garden Island HSF15.015.314.915.110.013.39.313.614.413.314.516.316.015.515.817.117.815.910.911.412.516.016.814.514.315.314.613.512.512.614.1
Gosnells City16.012.816.713.615.415.013.57.811.312.812.015.514.514.215.815.413.012.013.514.0
Jandakot Aero13.812.812.513.95.47.15.710.510.812.810.715.315.16.810.419.115.211.45.45.78.213.615.113.714.014.915.711.111.411.714.0
Medina Research Centre14.813.013.414.66.77.77.212.413.213.212.715.715.98.311.419.017.114.46.09.016.714.913.913.915.215.211.111.811.013.0
Pearce RAAF15.113.112.713.56.58.77.011.39.612.811.315.013.36.712.918.915.111.04.98.110.215.014.913.814.214.015.112.111.712.7
Perth Airport13.912.713.314.06.98.37.611.411.112.912.115.915.26.810.318.515.711.48.37.38.413.515.213.714.215.014.512.811.712.813.8
Perth Metro14.313.213.614.77.89.49.013.211.913.412.815.815.77.212.219.317.613.28.59.09.715.215.313.714.315.514.312.911.712.714.4
Rottnest Island15.416.215.214.414.015.015.015.813.713.816.116.215.713.916.317.817.015.112.112.514.918.016.414.614.515.315.014.012.813.615.0
Swanbourne15.015.513.014.69.911.412.214.013.214.113.916.015.213.513.919.317.115.38.19.912.116.714.713.413.915.414.711.211.912.313.8

This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.
The temperatures in this table are coloured by
their difference from the long-term average for the period
-10.0 -9.0 -8.0 -7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 +1.0 +2.0 +3.0 +4.0 +5.0 +6.0 +7.0 +8.0 +9.0 +10.0 °C difference from average


Daily rainfall
Central Coast (09) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Bickley - 0.2 3.2 - - - - 0.2 1.2 - 1.8 - 2.2 4.8 - - - 10.2 3.2 0.2 - - 5.6 - 22.2 0.6 23.0 0.2 - - -
Garden Island HSF - 1.0 0.2 - - - - 0.2 2.0 1.0 4.2 - 0.6 0.4 - - - 1.2 0.2 - - - 3.0 - 7.6 0.2 7.8 - - - -
Gosnells City - - 5.2 0.1 - - - - 0.8 - - - 0.8 - - - - 7.0 1.6 - - - 3.1 - 11.6 0.2 17.8 0.2 - - -
Jandakot Aero - 0.2 - - - - - - 24.6 - - - 1.4 1.0 - - - 8.8 0.4 - - - 2.0 - 11.8 - 8.8 - - - -
Jarrahdale - - 25.2 - - - 0.2 - 0.2 - - - 3.2 2.8 0.2 - - 9.4 3.2 - - - 3.4 - 9.8 0.6 9.2 0.6 - - -
Medina Research Centre - 1.0 0.3 - - - - 0.3 4.9 - - - 2.2 0.9 - - - 4.3 0.6 - - - 2.0 - 9.0 0.1 9.8 - - - -
Mundaring
0.2




0.8 0.2
7.2
1.0 2.6


11.0 5.2


9.4
29.4 2.2 13.0 0.4


Pearce RAAF - 0.2 - - - 0.2 -
- - 1.6 - 0.2 1.2 - - - 7.6 5.0 - - - 3.6 - 30.0 0.8 9.6 - - -
Perth Airport - - - - - - - 0.4 - - 0.2 - 0.8 1.0 - - - 9.0 1.2 - - - 2.8 - 24.8 0.2 21.8 0.2 - - -
Perth Metro - - - - - - - - - - - - 1.0 0.8 - - - 7.0 0.6 - - - 3.2 - 29.4 0.2 21.8 0.2 - - -
Roleystone









0.4
2.0



10.2












Rottnest Island - 1.0 - 1.0 - - - - 13.6 9.4 - - 0.2 0.2 - - - 3.4 0.4 - - 2.4 3.8 - 12.6 - 27.6 - - - -
Serpentine - - 11.2 - - - - - - - 4.4 - 1.2 2.0 - - - 7.4 3.2 - - - 2.4 - 8.8 - 2.4 0.2 - - -
Swanbourne - - - - - - 0.2 0.6 0.2 - 0.8 - 0.8 0.8 - - - 5.4 0.6 - - 1.8 4.4 - 21.4 - 27.2 - - - -

Most values are the precipitation in the 24 hours to 9 am on the day indicated. Days marked with »» are part of a longer accumulation, which is marked like this on the final day. Values over 100 mm have been rounded to the nearest whole millimetre. Days marked with - have a rainfall report of zero; days left blank have no rainfall report (which often indicates no rain fell).
This table is very wide; you may have to scroll sideways to see all the days, and you may need to set the paper to 'landscape' to print.


Notes

This statement was prepared before all data for the period were available. This may affect some of the statistics presented.

A Monthly Climate Summary is prepared to list the main features of the weather in Perth using the most timely and accurate information available on the date of publication; it will generally not be updated. Later information, including data that has had greater opportunity for quality control, will be presented in the Monthly Weather Review, usually published in the fourth week of the month.

This statement has been prepared based on information available at 3 pm on Monday 31 October 2011. Some checks have been made on the data, but it is possible that results will change as new information becomes available.

Averages are long-term means based on observations from all available years of record, which vary widely from site to site. They are not shown for sites with less than 10 years of record..
The median is sometimes more representative than the mean of long-term average rain.

The Rank indicates how rainfall this time compares with the climate record for the site, based on the decile ranking (very low rainfall is in decile 1, low in decile 2 or 3, average in decile 4 to 7, high in decile 8 or 9 and very high is in decile 10).
The Fraction of average shows how much rain has fallen this time as a percentage of the long-term mean.

Records in this summary are based on sites with at least 10 years of data.

*Official Perth observations have been recorded at several different sites with varying instrumentation over the years, and these changes can affect the continuity of the climate record. For the current Mt Lawley site, the most significant changes of this kind relate to minimum temperature and rain days.

For that reason, current mean temperature and rain-day data quoted here are based only on readings from the Mt Lawley site, which commenced observations in 1993. Sunshine recordings are from Perth Airport and for similar reasons current means use only Perth Airport data, which commenced in 1993.

For PDF files of Perth Metro climate statistics for other months, please click here for extremes and here for averages.

Further information

Media
(03) 9669 4057
Enquiries